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Power. Price. Service. No Compromises.BEIJING (Reuters) - Chinese scientists have developed a "Wing-In-Ground" (WIG) aircraft which can fly long distances just a few feet above the sea surface, state media said on Wednesday.

The plane can fly as low as half a meter (1 ft 7 ins) off the surface, hitting speeds of up to 300 km (180 miles) per hour and can carry up to 4 tonnes on takeoff.

"It's as safe as ships, although five or six times faster," associate professor Xu Zhengyu, vice-president of the research team at Tongji University in Shanghai, was quoted as saying.

"And it can carry much more weight than ordinary planes while costing half as much and using half as much fuel."

Wing In Ground effect refers to the reduction in drag experienced by an aircraft as it approaches a height approximately twice a wingspan's length off the ground or other level surface such as the sea.

Xu said the plane could be flown for military use and border control.

Tongji University planned to develop a 50-seat WIG by 2013, with 200 prototypes capable of carrying 200 to 400 tonnes scheduled for 2016 or 2017.

"Taking advantage of the aerodynamics of the ground effect, which adds extra lift when flying at very low altitudes, the aircraft can fly close to the water's surface," the China Daily said.

"This cuts back at least one third on fuel consumption, compared with standard planes of the same size, because the plane can benefit from air buoyancy."

The WIG has been listed as one of three types of aircraft given the green light in the general aviation field by the State Commission of Science Technology and Industry for National Defense, Xu was quoted as saying.

"However, the Civil Aviation Administration of China has yet to confirm aviation regulations at such low altitudes, which may become a problem," Xinhua said.

The development of the WIG ship, or Wing in Ground ship, which the government hoped to use as a next-generation marine transport, has stalled since the government has failed to find a private-sector partner. The WIG ship, dubbed a flying boat, is essentially an airplane that flies just above the surface of the sea at speeds of 250 to 300 km/h. The government and a private sector source each invested W85 billion (US$1=W938) to develop the vessel, aiming at commercialization by 2010. But the project has been stalled for almost two years since the government failed to find a private-sector partner after the original one withdrew.

An artist's rendition of the proposed WIG ship

According to shipbuilding industry sources on Thursday, STX Shipbuilding, the original private partner, withdrew from the project and DSME (Daewoo Shipbuilding and Marine Engineering) will decide if it will participate on Monday.

The industry is reluctant to participate in the development of the vessel since its economic benefits are not clear. The WIG is faster than other marine transport vessels, but its high speed could lead to collisions with islands or bridges. Also, the government has yet to sign a safety agreement with China, Japan or Taiwan which would be the likely end nodes of WIG ship routes.

The russians have been experienting with military WIG planes for some time - the Ekranoplane, and the Caspian Sea Monster.

While the concept of an armed combat role ( like the Russian Lun missile cruiser) sounds hokey, WIG aircrafts can supercede cargo ships for fast sea deployment, with a sizeable payload and much faster speed.

The russian Caspian Sea Monsters was designed for a payload of 1300 tons for a range of 10 000Nm. A squadron of these could actually make the R in RDF, a reality.

Couple of years back, Boeing explored the WIG concept with their version - the Pelican, that could either skim or fly.However, a vehicle that flies as well as "sail" ( known as Type C WIG )meant it was hated by both the Air Force and the Navy, and the concept died

Dwarfing all previous flying giants, the Pelican, a high-capacity cargo plane concept currently being studied by Boeing Phantom Works, would stretch more than the length of a U.S. football field and have a wingspan of 500 feet and a wing area of more than an acre. It would have almost twice the external dimensions of the world's current largest aircraft, the Russian An225, and could transport five times its payload, up to 1,400 tons of cargo.

Designed primarily for long-range, transoceanic transport, the Pelican would fly as low as 20 feet above the sea, taking advantage of an aerodynamic phenomenon that reduces drag and fuel burn. Over land, it would fly at altitudes of 20,000 feet or higher. Operating only from ordinary paved runways, the Pelican would use 38 fuselage-mounted landing gears with a total of 76 tires to distribute its weight.

The military, commercial and even space prospects for such a cargo plane—officially known as the Pelican Ultra Large Transport Aircraft, or ULTRA—are also huge.

The WIG concept is not dead in Russia KM is trying to find commerical avenues with smaller passenger versions While Beriev had also released a conceptual designThe Russian Beriev 2500 superheavy cargo transport design concept model for a Type C WIG craft.

i don't know abt this man... but isn't the waves gonna be a problem? Small minute air turbulences might affect the airflow over the ctrl surfaces. How about sudden tidal surges? is it gonna fly through lets say.. a 3m++ high swell? Why not just come up with a large hovercraft powered by jet engines.. -.- less bumpy ride, more cargo... How's the aircraft gonna change course btw when the wings are gonna touch the water when it rolls left/right?

Sea state - the most successful WIG company, the russian Ekranoplan; has vehicles that can adjust for flight heights to handle up to Sea State 5. Ekranoplan is the company who made the Caspian Monsters. Its a proven design that the russkies has no funds to put into mass-pro.

But stability is really relative to size. the bigger the better, the faster the better tooThere is a trade off between height and efficiency, so the WIG can actually fly higher than minimum height to null the effect of rogue waves, at the cost of some efficiency

Essential , remember that the WIG is a flying boat that rides on a cushion of air between the large lifting surfaces of the wings and the surface

Power/Weight Ratio , against Velocity

Hovercrafts can manage seastates well too, but they cannot reach the velocities of the WIGs.

WIG doesn't need to bank for turning, the turning radiuses are much bigger than that for relatively sized ships. But the ocean is a large place.

hmm~~~ faster the better... heavier the better... how abt sudden windshear? Turn radius = big.. umm... what happens when it needs to take evasive action to avoid collision with lets say... a submarine which just surfaced? Having WIGs can seriously affect shipping lines n naval ops... Ah.. well.. maybe they'll come up with something...

just to add in... if the WIGs use their large rudder to turn themselves, there's a lifting effect involved and will cause either wing to dip/rise : Speed of airflow over the inner ctrl surface in the wing is slower than the speed of airflow at the wingtips... and the faster the airflow, the greater the lift.. resulting in one of the wings (dependent on direction of turn) to dip... mmm my aerodynamics is a bit rusty.. hope i explained relatively clearly

hmm~~~ faster the better... heavier the better... how abt sudden windshear? Turn radius = big.. umm... what happens when it needs to take evasive action to avoid collision with lets say... a submarine which just surfaced? Having WIGs can seriously affect shipping lines n naval ops... Ah.. well.. maybe they'll come up with something...

just to add in... if the WIGs use their large rudder to turn themselves, there's a lifting effect involved and will cause either wing to dip/rise : Speed of airflow over the inner ctrl surface in the wing is slower than the speed of airflow at the wingtips... and the faster the airflow, the greater the lift.. resulting in one of the wings (dependent on direction of turn) to dip... mmm my aerodynamics is a bit rusty.. hope i explained relatively clearly

I've got no aerodynamics at all

Take in consideration how Ground Effect works, Its the normal way LIFT is obtained, minus downwash, which the "ground" negated and they became more lift. So a windshear from any direction, doesn't eliminate lift, but definitely create heck of a lot of turbulence.The problem of windshear on aircraft is a loss of lift, but with WIG, lift is never lost.

On collision, my guess is that why the latest designs and efforts are on type C WIG crafts - which can chose either to ride the WIG effect or simply fly up higher like a conventional plane. The difference being that making use of WIG optimises lift efficiency and speed.

When about to collide, you don't have to turn - just pull up. The killer problem will not be the Flying Height; but rather at 100-300km/h, how fast can a person react to pull up and avoid this. Possibly the WIG will mostly be on autopilot with an Automatic Collison-Avoidance system to forestall this

An excerpt from Aerospaceweb, on the relation between size of lift area, size of craft and ground effect lift

The Pelican is a logical extension of Rostislav Alexeiev's work. As big as the KM prototype was, it was simply too small to take full advantage of the benefits of ground effect. Indeed, Alexeiev had proposed much larger versions of the KM and Lun able to carry up to a thousand armed troops and their ground vehicles. The principal advantage of a WIG vehicle is the ability to move very heavy loads in a craft with a relatively small wingspan and low aspect ratio wing with great aerodynamic efficiency. Exemplifying this strategy is Boeing's claim that the Pelican is capable of transporting 750 tons over 10,000 nm (18,530 km) when cruising in ground effect, but can carry the same load only 6,500 nm (12,045 km) when out of ground effect.

So the WIG concept is clearly not new, and has been implemented by several manufacturers. However, none has really caught on, and the primary reason is that ground effect craft only become truly practical for very large vehicles, even larger than the massive KM. The reasoning is as follows. As discussed above, the amount of lift a flying vehicle needs to generate is directly related to its weight. The heavier a plane is, the more lift it needs, so the larger its wings must be (for the same cruise speed). This basic relation becomes a problem when we consider very heavy aircraft. As payload weight increases, wing size increases which requires larger and heavier structures that further increase overall weight. As weight increases, additional thrust and fuel is required to push the vehicle at its desired cruise speed over the required range, and the need for larger or additional engines plus greater fuel capacity further increases the overall weight of the vehicle. This trend pushes manufacturers towards increasingly complicated and expensive design solutions that make very large and heavy aircraft unprofitable to build.

However, the beauty of ground effect is that a given amount of wing area produces more lift near the ground than it would at high altitude. Or in other words, the same payload can be transported with a much smaller wing, which translates directly into a smaller, lighter, and more fuel efficient craft. It is therefore not surprising that most advocates of WIG vehicles have focused on very large vehicles, like Boeing's Pelican

Comments:1) Since such a "vessel" like Airfish 8 can cover 200km to 500km without refueling, does it made sense to use it for long maritime patrols along coastline? (assuming that high fuel consumption matter is solve)

2) Two countries stand out in building hugh size WIG vessels(Russia & China)...seems they have intention to use it for ferrying troops.

This post has been edited by Callsign 24 Seira on Oct 20 2007, 10:09 AM

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